LAMINAR BOUNDARY LAYER AROUND A CIRCULAR CYLINDER UNDER OSCILLATORY WAVES

Yuichi Iwagaki, Hajime Ishida

Abstract

A solution of water particle velocities in the boundary layer developed by monochromatic waves on the surface of a circular cylinder is obtained by applying the boundary layer approximations and perturbation method to the Navier-Stokes and continuity equations represented in the cylindrical coordinates. Since, in this process, it is necessary to give the velocity outside the boundary layer, the water particle velocities of diffracted waves around the cylinder are derived from MacCamy-Fuchs' velocity potential. Moreover, the occurrence of laminar flow separation is explained by using this solution. On the other hand, using a hydrogen bubble tracer some experiments have been performed about the water particle velocities of diffracted waves, velocity profiles in the boundary layer and occurrence of wake vortices. These results are compared with theoretical ones.